Harmonics of the AC susceptibility for the study of I-V curves in melt grown YBCO

TL;DR

This study investigates the harmonic response of AC susceptibility in melt-grown YBCO superconductors to understand their I-V characteristics and dissipative phenomena through Cole-Cole plot analysis.

Contribution

It introduces a novel application of harmonic analysis and Cole-Cole plots to extract detailed information about I-V behavior in YBCO superconductors.

Findings

Invariance of the Cole-Cole plot area with AC field variations

Reproduction of experimental features using a phenomenological resistivity model

Insights into dissipative phenomena in melt-grown YBCO samples

Abstract

The measurements of the 1st and the 3rd harmonics of the AC magnetic susceptibility, performed on melt grown YBCO samples as a function of the temperature and the external parameters (frequency and amplitude of AC magnetic field, intensity of a DC field) were studied by using the Cole-Cole plot analysis. By considering the AC field dependence of the 3rd harmonics Cole-Cole plots, we have extracted information about the peculiar behaviour of the I-V characteristics and, therefore, about the dissipative phenomena in the sample. The experimental results have been analysed with the help of both analytical and numerical curves. In particular, the use of a phenomenological expression for the resistivity allowed us to reproduce the main experimental features, including the observed invariance of the area inside the Cole-Cole plots and their behaviour as a function of the AC field.